Data from the partner services programme in New York City suggests that gay men who have previously used an HIV self-test tend to seek confirmatory testing without delay, according to an article published online ahead of print in Sexually Transmitted Diseases. The study also highlights socio-demographic differences between those using self-tests and other people with new HIV diagnoses, suggesting that the price of the kit discourages its use by those with lower incomes.

One of the main concerns about HIV self-testing (otherwise known as HIV home-testing) is whether people with reactive results will attend medical services for confirmatory testing. Additional tests are necessary as ‘false positive’ results do occasionally occur. If the initial result suggests infection with HIV, it must be confirmed with two more tests, using a different type of test kit each time. There is also a concern about whether people testing on their own, without a health professional present, may find a reactive result more difficult to cope with and be less likely to engage with the support and treatment services that they need.

Researching this issue is inherently challenging – as people use self-testing kits in private, health agencies and researchers cannot observe the results people get and track what individuals do next. The New York study attempts to shed light on the issue by examining data from people who used self-testing kits and who did seek confirmatory testing. But individuals who got reactive results during self-testing and did not seek any follow-up care are inevitably not included in this data set. We can only speculate as to how many such individuals there might be.

Staff at the New York City Department of Health and Mental Hygiene attempt to contact and offer partner services to all people newly diagnosed with HIV. Partner services include making contact with recent sexual partners of the newly diagnosed individual and offering them HIV testing. During interviews with newly diagnosed people, information on their HIV testing history is collected, including data on the previous use of self-testing.

Between January 2013 and August 2016, 8032 individuals were interviewed, of whom 127 (2%) reported having previously used an HIV self-test. Of note, while two-thirds had had a reactive result during self-testing, one-third had had a negative result.

Among people who gave an approximate date of their last self-test, 89% of those with a reactive result (39 of 44 people) sought a laboratory-based HIV test within one month of self-testing. In contrast, only 39% (14 of 36 people) with negative results had laboratory testing within a month of self-testing. In fact, their use of self-testing may have been many months prior to the laboratory testing at which they were diagnosed with HIV.

People who self-tested linked to care quicker than those who did not self-test: 91% of people who had used a self-testing kit linked to HIV treatment services within three months of their confirmatory HIV diagnosis, compared to 81% of people who had not used self-testing.

Compared with people who did not report self-testing, people who did use self-testing were significantly more likely to be male (96% vs 78%), be men who have sex with men (MSM) (92% vs 58%), report anal sex in the 12 months before HIV diagnosis (58% vs 34%), be white (46% vs 16%), have college or postgraduate education (67% vs 35%), and live in medium to high income ZIP codes of the city (51% vs 44%).

The researchers note the marked socio-demographic differences between people who had used self-testing and other people diagnosed with HIV. They say that this confirms that the $40 cost of the self-test kit takes it out of the reach of many people, including young black MSM and Hispanics, at high risk of HIV infection.

People who had used self-testing tended to test more frequently: 69% had tested at least once in the past two years, compared to 40% of those who did not use self-testing.

“Our study provides encouraging findings with regards to HIV confirmation after self-test and linkage to care once HIV infection is confirmed,” say the researchers. “Our results show that the rapid HIV self-test is in use by MSM who have high HIV acquisition risk and persons who self-tested positive sought timely confirmation of HIV infection and linkage to care.”